A lithography technique using a EUV light (Extreme Ultra Violet light) in the wavelength range around 13.5 nm is being developed for manufacturing a semiconductor device with a fine structure, such as a MEMS (Micro Electro Mechanical Systems), and the like. A reflective photomask used for the lithography in the extremely-short wavelength region comprises, for example, a multilayer film mirror, which includes alternately stacked molybdenum (Mo) layer and silicon (Si) layer, and a light-absorbing body. Further, such a reflective photomask is required to have a high-level uniformity in a pattern size thereof.